Passengers crowd the halls and counters at Soekarno-Hatta Airport in Tangerang as monitors show cancelled flights after the Anak Krakatau eruption.

Indonesia kept several airports closed and shifted schools to remote learning on Monday as volcanic ash coated parts of Java and Sumatra. The eruption has halted about 2,300 flights and affected more than 268,000 passengers.

Authorities say the volcano remains active with intermittent eruptions and ash emissions. The Geological Agency said the 25-hour eruption ended on Sunday but warned that more activity is likely in the coming days.

Volcanic ash in the airspace around Jakarta and other cities prompted the closure of eight airports. Schools in affected areas moved to online learning to reduce exposure.

Indonesia sits on the Pacific 'Ring of Fire' and has more than 120 active volcanoes.